Lateral bores and wells are used to:
1. Create a drainage point at some distance from a central location;
2. Open a lengthy section of a formation to flow;
3. Provide for fluid injection;
4. Heat large volumes of the earth; and
5. Form part or all of a flow path to another well.
A preferred method of boring and casing lateral bore holes, which do not slant from the point of origin, is described below. Using standard drilling equipment and beginning with a vertical, or nearly vertical, well, the hole is deviated in a desired direction in such a way that it is an angle of say 45 degrees from vertical when it approaches the stratum where a horizontal bore hole is required. A usual casing string is set and cemented and the shoe is drilled. Angle gain is increased to some predetermined quantity and drilling a curved hole is continued until it becomes horizontal in the desired stratum. The more acutely curved part of the hole may be underreamed to increase its diameter by some 20 to 40 percent to accommodate more readily the passage of a larger casing and a more powerful drilling device as described later. The drilling apparatus for a small radius of curvature bore hole is then set aside and that for a straight hole is assembled.
Steel pipe normally is used as casing in deviated wells. However, the weight and lack of flexibility of steel pipe used with conventional drilling equipment severely limits the usefulness of steel casing in long lateral wells or in highly curved bore holes. Likewise, steel pipe usage creates similar problems in the drilling of lateral wells. As indicated below, various attempts have been made to improve the art of lateral well usage in hydrocarbon recovery.
The U.S. Pat. No. to Grable 4,024,913, describes a high strength, light weight, non-metallic material which may be used in making oil tubulars.
The U.S. Pat. No. to Jeter 3,893,523, discloses a drill string which may be curved. It is made of two or more coaxial members.
The U.S. Pat. No. to Allen 3,055,424 shows a tubular shaft comprised of a plastic middle member and top and bottom members of metal.
The U.S. Pat. No. to Hennigh 2,650,314, discloses that outwardly bowed spring centralizers in contact with the walls of a bore hole to restrain rotation of a motor housing.
The U.S. Pat. No. to Driver 4,227,584, shows a plurality of electric motors motors with their shafts connected by flexible couplings
V. P. Singh, et al, wrote "The Flow of Sand/Water Slurries In Horizontal Pipes With Internal Spiral Ribs--Effect of Rib Height." It appeared in The Canadian Journal of Chemical Engineering, Vol. 54, Aug., 1976. C. A. Shook's article "The Effect of Line Length for Inclined Slurry Pipelines at Shutdown" was reported in The Canadian Journal of Chemical Engineering, vol. 53, Dec., 1975. In World Oil, Dec. 1978. Anderson and Hutchison report on "How to Efficiently Wash Sand From Deviated Well Bores."
Methods of boring small radius lateral bore holes from vertical wells are disclosed in the U.S. Pat. No. to Holbert 3,398,804 and to U.S. Pat. No. to Jeter 4,007,797. Such sharply curved holes have two distinct disadvantages: firstly, a casing is difficult to run and secondly, the distance that can be drilled with directional control is limited.